Pitch control in paper making



April 24, 1956 File Z 502 .er /oa//VE H. E. coRBlN ETAL 2,743,179

FITCH CONTROL IN PAPER MAKING d July 22, 1953 April 24, 1956 H. E. coRBlN ETAL 2,743,179

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AGEA/7' April 24y 1956 H. E. coRBlN ETAL FITCH CONTROL IN PAPER MAKING 3 Sheets-Sheet 3 Filed July 22, 1955 United Sttes 2,743,179 Patented Apr. 24, i956 ice PIT CH CGNTROL 1N PAPER MAKING Harold Emery Corbin, Arlington, Mass., and `lohn Clark Dean, Port Washington, N. Y., assignors to Socony Mobil Oil Company, Inc., a corporation of New York Application July 22, 1953, Serial No. 369,608

Claims. (Cl. 92-9) The present invention relates to the control of pitch in paper making and accelerated cooking particularly in the sultite method of pulping.

In general, the efforts exerted in the past to control pitch in paper making have centered around attempts to remove pitch from the machines involved after the pulp is dumped from the digester. It now has been found that pitch can be controlled from its very inception and a much faster cooking operation achieved by introducing a pitch solvent and a non-ionic, an anionic or a cationic emulsifier into the digester.

Pitch is troublesome in paper furnishes containing groundwood and suliite pulp, particularly when the latter s unbleached. The problem has been considerably aggravated by the use of green-imaged wood which the paper industry has been forced to use in recent years, and which it will continue to use for quite some time.

It has been found that the use of an emulsion of a highly aromatic solvent in the presence of a critical amount of a non-ionic, an anionic or a cationic emulsier, or in general an emulsiter or dispersing agent effective in acid medium of say pH 5-6, results in:

(a) A marked decrease in cook cycle,

(b) A decided improvement in screening conditions and pulp cleanliness, Y

(c) Reduction in shut-down time in the Fourdrinier operation and in the operation of the cyclinder machines,

(d) More eifective control of slime and bacterial growth and,

(e) An improved quality pulp.

The etlicacy of the pulping agent of the present invention was completely demonstrated on a full plant scale in a pulp mill having eight horizontal indirect cook digesters, each of ten tons nished pulp capacity and charged by a gravity acid system and a small cylinder machine which operates on slush pulp and produces light weight free sheets such as twisting, waxing and carbonizing grades. Operated as a separate unit in conjunction with the pulp mill is a single Fourdrinier paper machine which also manufactures light weight free sheets.

Mill records establish that during test periods of several weeks after continued use of the novel pulping accelerator and pitch dispersant that there was an average increase in tonnage of approximately 25 per cent. This is attributed to a shortened and more uniform cooking cycle and to markedly improved screening conditions. In addition, there was a reduction of slime in the winter months without the use of chemicals for bacteria control while in the warm weather a sizeable reduction of bactericide` was possible.

Furthermore, although the actual consumption of Chlo-.f

rine in bleaching operations has not been noticeably reduced, there has been a noticeable increase in the brightness of the pulp with equivalent amounts of bleaching agent.

Generally, the pitchcontrol and pulp penetrant is added directly to the digester for optimum results either through the acid line feeding into the digester or by other means such as with the wood chips.

When the novel pitch dispersant and cooking accelerator was first added to a digester charge in the mill it was noticed that after about 90 hours of operation at the rate of about an amount of reagent equal to the amount of pitch in the wood being digested, extremely large pitch balls suddenly appeared in the beater furnishing stock to the cylinder machine. This beater was charged with per cent to per cent of unbleached slush pumped directly from the pulp mill and l() per cent to 20 per cent of bleached laps.

From the dark appearace of the agglomerated materal, it was evident that this was pitchy material which had been deposited previously. Close inspection of the screens, the Kaymr cylinder and press section confirmed the foregoing since it was manifest that old deposits of pitch were being removed gradually. In spite of this excessive amount of old pitch, no ditheulty was'caused in the operation of the Kaymr machine.

Thereafter, the novel reagent was added at the rate of 5 to 10 gallons of reagent per digester charge.

By the use of novel reagent, a quicker cook is achieved. This is clearly shown by the graphs Figures I, II, II and IV. The progress of the cook is determined by measurement of the free sulfur dioxide and the cook is regarded as completed when the sulfur dioxide content drops to 0.2 per cent or less. These data represent several typical periods when the novel reagent was used and when it was not used. In general, the slope of the graphs of cooksv without the novel reagent indicate that after a slow initial out in the presence of the novel reagent, the reduction in sulfur dioxide content proceeds more rapidly earlier in the digestion cycle, indicaing a definitely quicker' cook due to earlier penetration of the wood chips by the digester liquid.

The curves in Figure Il derived from data on cooks made without the addition of the novel reagent but after the initial use thereof lfollow the same pattern as those based upon data obtained while adding the novel reagent and establish the residual effect of the novel reagent.

Operation of this mill, as data for the past several years indicates, involves the devotion of eight to twelve hours every two to three weeks for cleaning the system. Screen capacity being the limiting factor, this has resulted in a production loss of three to ve tons of pulp per hour of shutdown time or an average loss of iifty tons per shutdown. It has been established that when the novel reagent is used, the period between shutdowns can be lengthened greatly. During the test period the interval between shutdowns was extended to an average of ten weeks instead of two or three.

As a result of better screening conditions, the amount of tailings is less. The knot rejects from pulp digested in the presence of the novel reagent are softer and contain less entrapped fiber.

In view of theforegoing, it is evident that the present invention provides a means of reducing pitch trouble in sulte andgroundwood pulpingrnillsV and Linvolves adding the novel reagent to the digesters in the sulfite pulping process or to the groundwood in the mechanical process.

The eiect of the novel pitch dispersant and pulp penetrant is best recognized from the following interpretation of the records of cook cycle time for the period from November of one year to March of the next succeeding year. Upon the addition of the novel pitch dispersant and pulp penetrant, there was no pronounced fluctuations in cycle time and the cycle time became less until it reached a minimum. The use of the novel reagent was stopped on January 22'according to the pre-arranged plan but the residual eiect was apparent until January 28. Thereafter, the time of the cooking cycle increased and became irregular until February 17 when 10 gallons of reagent were added. The effect of the addition of the reagent was not manifest until February 20 when the time of the cycles became less and the fluctuations ceased. This is depicted graphically in Figure V.

In general, the novel pitch dispersant and pulp penetrant comprises a solvent for pitch or resin and non-ionic, anionic or cationic emulsier. It is preferred to use a high solvent power aromatic oil such as xylene, methyl naphthalenes or, in general, a solvent having a mixed aniline point of 125 F. maximum together with a non-ionic or anionic or cationic emulser such as gums, proteins, amines, amine soaps, sulfonates, etc. ln order to facilitate the use of the novel reagent, itis also preferred to add the pitch dispersant and pulp penetrant to the pulping system as an emulsion containing per cent vto 75 per cent of solvent or base oil and 0.5 per cent to 15.0 per cent of the emulsifier and the balance water. The emulsion so produced is stable in storage and may be subjected to high dilution with water or with acids of the strength customarily usedin the sulfite pulping process.

Typical and illustrative of the suitable solvents or base oils are the following cycle oils from a catalytic cracking operation:

n A i A n n HA!! H13!! U C!! A. P. I. Gravity 20.@ 23.6 10. 0 Flash Point (COC), F 17o 10o 260 Pour Point, F 0 0 Viscosity at 100 F. S. U 32. 9 37 Mixed Anilinc Point, F 88.0 97. 9 59 7 IBI;` 352 416 496 404. 474 516 494 521 536 549 596 585 600 691 668 Base oil or solvent A comprises primarily mono-substituted alkyl naphthalenes; base oil or solvent C comprises predominantly di-substituted alkyl naphthalenes; and base oil or solvent B comprises monoand di-substitutcd alkyl naphthalenes.

Typical of the emulsifiers is the soap formed by the reaction of a carboxylic acid such as acetic acid and a primary aliphatic amine of the type RNHz where R isan alkyl radical of 8 to 2O carbon atoms. This cationic emulsier may be used in the range of 0.75 per cent to 3 per cent amine with the molecular equivalent of the carboxylic acid. Thus, for example, the base oil emulsion may be made by using 1 per cent of RNHz and l per cent acetic acid as an emulsier.

yThe emulsion is most readily and preferably prepared with a minimum amount of emulsier and a maximum amount of base oil under conditions of high shear in a mechanical homogenizer while maintaining the resultant product in a condition of fluidity. The concentration of the base oil or solvent may vary from 35 per cent to 75 per cent. Thus, for example, a satisfactory pulping adjunct comprised Solvent percent-- 70 Emulsitier ydo '2 pH Y l '3.5 to'4r5 Weightfper gal., 1bs.. 7.9

Aromatic petroleum faction having gravity of 13-17" A. P. I. and boiling range of about 350 to about 600 F.

2 Alkali metal alkyl aryl sulfonate, sold under trade name of Mara= Speltslim ghetti.

4 Sodium nitrite.

Sodium salt of pcntuehlorophenol.

0 Form-.ihn (aqueous 37% formaldehyde).

The essential constituents .are the aromatic solvent and the emulsier or dispersing agent. However, it has been found, particularly when using protective colloids of the nature of organic materials such as gums, that a preservative such as Dowcide 6, preferably in combination with formalin, are desirable in .order to prevent decompositionv of the natural organic material of-which so many protective colloids suchl as the natural ,gums are composed. Sodium nitrite vor any other suitable corrosion inhibitor is desirable to inhibit corrosion during storage of the emulsion inmetal containers such as shipping containers. Thus, while the essential constituents are the aromatic petroleum fraction orother highly aromatic.. solvent, theemulsier, non-ionic, anionic or cationic, and water, it is preferred to incorporate the corrosion inhibitor and the preservative or zpreserva'tives in the emulsion.

The presently preferred pulping adjunct can be prepare by adding the Yemulsifiers or dispersing .agents Marasperse N and Gum ghatti, corrosion inhibitor and high boiling preservative to water with agitation and. heating to about 170 F. to completel solution. Thereafter, the solvent is added, the mixture homogenized and cooled to about F. When cooled, the formalin is mixed with the cooled mixture and the pulping adjunct is ready for packaging.

When adding the `pulping adjunct to the pulping system, it is preferred to introduce an amount of the adjunct, i. e., emulsion into the pulping system to supply about 0.1 per cent to 1.0 per cent'based on the total mass lof librous materials charged,i. e.,'wood chips.

This application is a continuation-impart of our application Serial No. 21,668, tiled April 17, 1948.

We claim:

l. The improvement in the pulping of wood by the sulfite process which comprises adding to the digester 0.1 to about 1.0 per cent based on total fiber charge to the digester of an emulsion comprising about 35 `to about 75 per cent `of an aromatic petroleum fraction 'having a mixed aniline point of about F. (maximum), about 0.5 to about 1550 per cent of an emulsifler effective at pH of about 5 to vabout 6, and the balance water and digesting said fibre charge in the presence of said emul-' sion.

2. The improvement in the pulping of wood by the sulfite process which comprises digesting wood .chips in the presence of' about 2 to about 5 gallons o'fV an emulsion `to `aboutten tons of wood chips, said emulsion comprising about 40 to about 70 weight per cent ofan aromatic fraction 'of mineral oil having an A. P. I. gravity of about 10 to about 24, a ash point (COC) of about 17'5 to about 260 F., a viscosity at 100 F. of about 32 to vabout 37 seconds S. U. V., a mixed aniline point of about `59'to about 98 F., a 10% point of about 400 F. to about '52.0" F. and a 90% point of about 545 F. to aboutk 585 v F., about0;5 'to about 10.0 weight per 'centfof an anionic'femulsifier, aboutlliZl to about 2.0 weight lper cent of a protective colloid and Athe balance Wafl.

3. The improvement in the pulping of wood by the sulte process which comprises digesting wood chips in the presence of about 2 to about 5 gallons of an emulsion to about ten tons of wood chips, said emulsion compn'sing about 40 to about 70 weight per cent of an aromatic fraction of mineral oil having Gravity A. P. I., about 10 to about 24 Flash point (COC), about 175 to about 260 F.

S. U. V. 100 F., about 32" to about 37 Mixed aniline pt., about 59 to about 98 F.

% point, about 400 to about 520 F. 90% point, about 545 to about 585 F.

about 0.5 to about 10 weight per cent of alkali metal lignin sulfonate, about 0.2 to about 2.0 weight per cent Gum Ghatti and the balance water.

4. The improvement in the sulfite pulping of wood which comprises digesting wood chips in the presence of about 0.1 to about 1.0 per cent based upon the total weight of wood chips of an emulsion comprising about 40 to about 70 weight per cent of an aromatic fraction of mineral oil having Gravity A. P. I., about 10 to about 24 Flash point (COC), about 175 to about 260 F.

S. U. V. @l 100 F., about 32" to about 37 Mixed aniline point, about 59 to about 98 F.

10% point, about 400 to about 520 F. 90% point, about 545 to about 585 F.

about 0.5 to about 10 weight per cent of sodium lignin sulfonate, about 0.2 to about 2.0 weight per cent Gum ghatti and the balance water.

5. The improvement in the pulping of wood by the sulte process which comprises digesting wood chips in the presence of about 0.1 per cent to about 1.0 per cent based on the total mass in the pulping system of an emulsion comprising about 35 per cent to about 75 per cent of an aromatic petroleum fraction having a mixed aniline point of about 125 F. maximum, about 0.5 per cent to about 15.0 per cent of an emulsifier eiective in acid medium and the balance water.

6. The improvement in the pulping of wood by the sulfite process which comprises digesting wood chips in the presence of about 2 to about 5 gallons of an emulsion to about ten tons of wood chips, said emulsion comprising about 38 per cent to about 25 per cent of an aromatic fraction of mineral oil having an A. P. I. gravity of about 10 to about 24, a ash point (COC) of about 175 to about 260 F., a viscosity at 100 F. of about 32 to about 37 seconds S. U. V., a mixed aniline point of about 59 to about 98 F., a 10% point of about 400 to about 520 F. and a 90% point of about 545 to about 585 F., an emulsiiier eiective in acid medium and the balance water.

7. The improvement in the pulping of wood by the sulte process which comprises digesting wood chips in the presence of about 2 to about 5 gallons of an emulsion to about 10 tons of wood chips, said emulsion comprising about 38 per cent to about 25 per cent of a pitch solvent comprising an aromatic petroleum fraction containing primarily alkyl naphthalenes, an emulsifier consisting essentially of about 0.75 to about 3% of a primary aliphatic amine having an alkyl group of 8 to 20 carbon atoms and a molecular equivalent of acetic acid, and the balance water.

8. The improvement in the pulping of wood by the sulite process which comprises digesting wood pulp in the presence of about 0.1 per cent to about 1.0 per cent based on the total mass in the pulping system of an emulsion comprising about 35 per cent to about 75 per cent of an aromatic petroleum solvent having a gravity of about 10 to about 24 A. P. I., a ash point (COC) of at least about 175 F., a mixed aniline point of about 59 to about 98 F. and a boiling range of about 352 F. to about 691 F., about 0.5 per cent to about 15.0 per cent of an emulsier consisting essentially of about 0.75 to about 3 of a primary aliphatic amine having an alakyl group of 8 to 20 carbon atoms and a molecular equivalent of acetic acid, an dthe balance water.

9. The improvement in the pulping of wood in the sulte process which comprises digesting wood chips in the presence of about 2 to about 5 gallons of an emu1- sion to about 10 tons of wood chips, said emulsion comprising about 35 to about 75 per cent of an aromatic petroleum fraction having a mixed aniline point of about 125 F. maximum and comprising primarily alkyl naphthalenes, an emulsiier consisting of molecular equivalents of a lower aliphatic monocarboxylic acid having not more than 5 carbon atoms and a primary aliphatic amine hav ing an alkyl radical of about 8 to about 20 carbon atoms and the balance water.

10. The improvement in the pulping of wood in the sulfite process which comprises digesting wood chips in the presence of about 2 to about 5 gallons of an emulsilier to about 10 tons of wood chips, said emulsion comprising about 35 per cent to about 75 per cent of an aromatic petroleum fraction having a distillation range of about 200 F. to about 700 F., having a liash point of about F. to about 300 F. and a mixed aniline point of about 59 to about 100 F., an emulsier consisting essentially of molecular equivalents of acetic acid and a primary aliphatic amine in which the fatty acid radical has about 8 to about 20 carbon atoms.

References Cited inthe tile of this patent UNITED STATES PATENTS 531,856 Partington Jan. 1, 1895 1,103,336 Aktschourin July 14, 1914 1,945,862 McIntyre Feb. 6, 1934 2,144,756 Fritz Jan. 24, 1939 FOREIGN PATENTS 673,318 France Jan. 14, 1930 66,695 Austria Sept. 25, 1914 663,444 Germany Aug. 6, 1938 

1. THE IMPROVEMENT IN THE PULPING OF WOOD BY THE SULFITE PROCESS WHICH COMPRISES ADDING TO THE DIGESTER 0.1 TO ABOUT 1.0 PER CENT BASED ON TOTAL FIBER CHARGE TO THE DIGESTER OF AN EMULSION COMPRISING ABOUT 35 TO ABOUT 75 PER CENT OF AN AROMATIC PETROLEUM FRACTION HAVING A MIXED ANILINE POINT OF ABOUT 152* F. (MAXIMUM), ABOUT 0.5 TO ABOUT 15.0 PER CENT OF AN EMULSIFIER EFFECTIVE AT PH OF ABOUT 5 TO ABOUT 6, AND THE BALANCE WATER AND DIGESTING SAID FIBRE CHARGE IN THE PRESENCE OF SAID EMULSION. 